The present invention pertains to a roller assembly for use with a bending apparatus and a bending apparatus employing a roller assembly of the present invention. More specifically, the roller assembly has split roller dies which are pivotably retained on the roller assembly to accommodate variations in external dimensions a workpiece being bent thereagainst.
A variety of bending apparatus for bending conduits, bars, and the like are available. Many bending apparatus include a bending shoe and a roller assembly. The bending shoe is a partially circular body having several channels of varying diameters formed on the circumference of the shoe. A keeping segment is often provided on one end of each of the channels to retain a piece of conduit in a portion of the channel. The shoe is rotated to wrap a piece of conduit around a selected circumferential channel. The free end of the conduit, the end which is not retained by the keeping segment, moves along a roller assembly which promotes movement of the conduit relative to the bending shoe while the bending shoe is rotating to bend the conduit.
Often, when the bending apparatus has several channels formed around the circumference of the shoe, a corresponding group of rollers will be provided on the roller assembly. For example, a shoe which has two circumferential channels will have two rollers on the corresponding roller assembly. The two rollers will be positioned in a cooperative arrangement so that they promote movement of the free end of the conduit as the conduit is wrapped around the channel on the bending shoe.
Such bending apparatus are used in various industries including construction and plumbing. Metal conduit and pipe are manufactured in various nominal diameters having various wall thicknesses which are generally referred to as aluminum or steel "rigid" conduit and pipe, IMC conduit, or "thin wall" (EMT) conduit. A problem arises when bending large diameter thin wall conduit and pipes, the relatively thin wall of this type of conduit and pipe tends to collapse inwardly or kink and distort during bending. Kinking and distorting occurs when the outer surface of the conduit is not intimately supported during bending.
In order to provide support for variety of conduit diameters, shoes with a variety of bending channel diameters have been provided. The corresponding roller assembly matches and accommodates the diameter of the bending channels on the bending shoe. A problem arises when bending conduit in that the rollers employed in the roller assembly are usually fixed rollers which do not accommodate variations in the conduit which is being bent. A problem arises as the conduit is bent around the shoe such that the free end (the end moving through the roller assembly) tends to become distorted. This problem is exacerbated by large diameter thin wall conduits.
A device as shown in U.S. Pat. No. 4,546,632 issued Oct. 15, 1985, to van den Kieboom et al. shows a roller assembly which has a split roller which allows axial movement of the roller sections along a shaft. The device in van den Kieboom et al. has a problem in that axial movement along a shaft of the roller halves or roller dies does not intimately support the cylindrical outer surface of a workpiece being bent thereagainst. As such, the device as shown in van den Kieboom does not prevent crimping or distortion of the outer surface of the conduit during the bending operation. Further, the device as shown in van den Kieboom requires manual adjustment in order to accommodate different conduit dimensions.